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• GWP of housefly larvae treatment is significantly higher in summer than in winter. • Bioconversion itself contributed very little to GWP. • GWP will increase slightly when larvae are stored by drying rather than freezing. • There is a contradiction between a higher mature larvae production and a lower GWP. The significant increase in the demand for biomass waste treatment after garbage classification has led to housefly larvae treatment becoming an attractive treatment option. It can provide a source of protein while treating biomass waste, which means that nutrients can be returned to the natural food chain. However, the performance of this technology in terms of its environmental impacts is still unclear, particularly with regards to global warming potential (GWP).This study used a life cycle assessment (LCA) approach to assess a housefly larvae treatment plant with a treatment capacity of 50 tons of biomass waste per day. The LCA results showed that the 95% confidence intervals for the GWP in summer and winter were determined to be 24.46–32.81 kg CO 2 equivalent (CO 2 -eq)/ton biomass waste and 5.37–10.08 kg CO 2 -eq/ton biomass waste, respectively. The greater GWP value in summer is due to the longer ventilation time and higher ventilation intensity in summer, which consumes more power. The main GWP contributions are from (1) electricity needs (accounting for 78.6% of emissions in summer and 70.2% in winter) and (2) product substitution by mature housefly larvae and compost (both summer and winter accounting for 96.8% of carbon reduction). [Display omitted] [ABSTRACT FROM AUTHOR]

Background: The interaction among microorganisms in the anaerobic digestion of food waste (ADFW) reactors lead to the degradation of organics and the recycling of energy. Viruses are an important component of the microorganisms involved in ADFW, but are rarely investigated. Furthermore, little is known about how viruses affect methanogenesis. Results: Thousands of viral sequences were recovered from five full-scale ADFW reactors. Gene-sharing networks indicated that the ADFW samples contained substantial numbers of unexplored anaerobic-specific viruses. Moreover, the viral communities in five full-scale reactors exhibited both commonalities and heterogeneities. The lab-scale dynamic analysis of typical ADFW scenarios suggested that the viruses had similar kinetic characteristics to their prokaryotic hosts. By associating with putative hosts, a majority of the bacteria and archaea phyla were found to be infected by viruses. Viruses may influence prokaryotic ecological niches, and thus methanogenesis, by infecting key functional microorganisms, such as sulfate-reducing bacteria (SRB), syntrophic acetate-oxidizing bacteria (SAOB), and methanogens. Metabolic predictions for the viruses suggested that they may collaborate with hosts at key steps of sulfur and long-chain fatty acid (LCFA) metabolism and could be involved in typical methanogenesis pathways to participate in methane production. Conclusions: Our results expanded the diversity of viruses in ADFW systems and suggested two ways that viral manipulated ADFW biochemical processes. 3DQb7S-2dM-gGjfqAhcADy Video Abstract [ABSTRACT FROM AUTHOR]

[Display omitted] • The environmental impact of rural solid waste management was quantified. • Waste separation helps decrease the environmental impact of landfill. • Electricity from rural WTE is as carbon-intensive as that from coal power plant. • Improving energy recovery efficiency of WTE cuts off the GHG emission drastically. Rural solid waste management is essential for fulfilling sustainable development goals, especially in developing countries. However, quantitative study on this aspect has been little and far behind the urban areas. In this study, the environmental impacts of four typical rural solid waste management systems were quantified using life cycle assessment based on data from field investigations of five towns across four seasons. Sensitivity analysis was used to determine the most influential parameters. The results showed that landfilling mixed waste contributed the highest environmental impacts. By substituting landfilling with incineration, the environmental impacts (i.e., global warming potential, terrestrial acidification potential, fossil resource scarcity, freshwater ecotoxicity potential) dropped about 110%-900%. When shifting collection schemes to source separation, the environmental impacts also decreased by approximately 50%-200%. However, the environmental impacts of applying source separation to the existing management systems with mixed collection and disposal facilities of landfill or waste-to-energy (WTE) incineration are unclear and depend on the performance of decentralized composting and anaerobic digestion facilities, which need further investigations. Compared with urban cases, the landfill in rural areas emits higher greenhouse gas (GHG), and WTE incineration plants in rural areas have similar GHG emissions to WTE in urban areas. Besides, energy recovery was the most influential process in WTE systems and a 1% improvement on that would bring over 10% progress on global warming potential impact category. These findings can be useful for improving and developing rural domestic waste treatment in China and other developing countries. [ABSTRACT FROM AUTHOR]

The greenhouse gas (GHG) emissions from waste sector have drawn a lot of attention in the effort to achieve worldwide net-zero emissions. Current studies of GHG emissions from waste treatment are mostly calculations based on a specific spatiotemporal point or hypothetical scenario, but research on the timeline is insufficient. This study assesses and predicts the GHG emissions on the timeline as waste treatment technologies develop in Shanghai from 1991 to 2025 using the Life Cycle Assessment (LCA) methodology. The findings demonstrate that GHG emission peaked in 2001 of 1490.48 Gg CO 2 -eq and reached net-zero in 2019 owing to the application of alternative technologies and waste segregation. The waste characteristics is the most sensitive parameter, emphasizing the significance of meticulously collecting local waste characteristics data. This study offers an approach for other nations or localities to use when researching the GHG emissions on the timeline of waste treatment systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Acid crisis characterized by acid accumulation and/or low pH is a common reason for the failure of anaerobic digestion (AD), which is usually applied for wastewater and waste treatment. Acid-tolerant methanogens are rarely reported to be active in the artificial anaerobic digester. In this study, we observed that the thermophilic methanogenesis by a consortium in the form of flocs and not granules could still be recovered during long-term operation at acetate concentration of up to 104 mM and pH 5.5 by adjusting the pH gradually or directly to pH 5.5 or 5.0. The acclimation process involving the gradual decrease in pH could enhance the resistance of the consortium against extreme acidification. The stable isotopic signature analysis of biogas revealed that Methanosarcina , which produced methane through acetoclastic methanogenesis (AM) pathway, was the predominant methane producer when the pH was decreased gradually to 5.0. Meanwhile, the abundance of Coprothermobacter increased with a decrease in pH. Contrastingly, when directly subjected to an environment of pH 5.5 and 104 mM acetate (15.84-mM free acetic acid) after a 42-day lag phase, Methanothermobacter was the predominant methanogen. Methanothermobacter initiated methane production through the hydrogenotrophic pathway and formed syntrophic relationship/consortium with the potential acetate-oxidizing bacteria, Thermacetogenium and Coprothermobacter. Comparative metagenomic and metatranscriptomic analysis on this self-adapted and acid-tolerant consortium revealed that the genes, such as GroEL, DnaK, CheY, and flagellum-related genes (FlaA, FlgE, and FliC) from Anaerobaculum , Thermacetogenium , and Coprothermobacter were highly overexpressed in response to system acidification. Microbial self-adaptation patterns (community structure adjustment, methanogenesis pathway shift, and transcriptional regulation) of thermophilic methanogenic consortium to gradual and sudden acidification were evaluated by integrated stable isotopic signature and comparative meta-omic approaches. The study elucidated the acid-resistant mechanism of thermophilic methanogenic consortium and deepened our knowledge of the function, interaction, and microbial characteristics of Methanosarcina , Methanothermobacter , and Coprothermobacter under extreme acidic environment. [ABSTRACT FROM AUTHOR]

This investigation evaluated the effectiveness of biochar of different particle sizes in alleviating ammonium (NH 4 + ) inhibition (up to 7 g-N/L) during anaerobic digestion of 6 g/L glucose. Compared to the control treatment without biochar addition, treatments that included biochar particles 2–5 mm, 0.5–1 mm and 75–150 μm in size reduced the methanization lag phase by 23.9%, 23.8% and 5.9%, respectively, and increased the maximum methane production rate by 47.1%, 23.5% and 44.1%, respectively. These results confirmed that biochar accelerated the initiation of methanization during anaerobic digestion under double inhibition risk from both ammonium and acids. Furthermore, fine biochar significantly promoted the production of volatile fatty acids (VFAs). Comparative analysis on the archaeal and bacterial diversity at the early and later stages of digestion, and in the suspended, biochar loosely bound, and biochar tightly bound fractions suggested that, in suspended fractions, hydrogenotrophic Methanobacterium was actively resistant to ammonium. However, acetoclastic Methanosaeta can survive at VFAs concentrations up to 60–80 mmol-C/L by improved affinity to conductive biochar, resulting in the accelerated initiation of acetate degradation. Improved methanogenesis was followed by the colonization of the biochar tightly bound fractions by Methanosarcina . The selection of appropriate biochar particles sizes was important in facilitating the initial colonization of microbial cells. [ABSTRACT FROM AUTHOR]

An integrated approach was applied to identify the key odorants comprising emissions from different zones in two adjacent waste treatment facilities (an aerobic biological treatment plant and an anaerobic landfill site), identify their precise sources, and distinguish the interactive influences between them. Seven odor families were investigated, including alcohols, terpenes, carbonyls, aromatics, volatile fatty acids (VFAs), sulfur compounds, and ammonia. Principal components analysis, characteristic molecular ratios, and ternary diagrams were used to differentiate the interactive influence of the odor sources. Among typical biotic compounds, terpenes were found to be more suitable as odor markers for their better fingerprinting character than sulfur compounds and VFAs. Ratios ofp-cymene at sampling locations related to the biological treatment plant (aerobic status) were between 0.00 and 0.25, whereas those at landfill-related sampling points (anaerobic status) were between 0.25 and 1.0. The molecular ratio of terpenes was also found to be an appropriate means to differentiate between homologous and similar odor sources such as an aerobic biological treatment plant and anaerobic landfill. Implications: The aim of this work is to identify the key odorants comprising emissions from different zones in two adjacent waste treatment facilities, identify their precise sources, and distinguish the interactive influences between them. The emission of gaseous pollutants greatly affects the living quality of nearby residents, and odor complaints are becoming a major problem. In this study we utilized various pretreatment and analytical methods to obtain integrated emission information of gaseous pollutants. The results showed terpenes were found to be more suitable as odor markers for their better fingerprinting character than sulfur compounds and VFAs. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) properties and parameters for MSW treatment technologies are decisive for GHG emission of MSW treatment systems. But they are changing in China due to MSW source segregation and technological advancements, which requires new studies on GHG emissions of MSW treatment systems based on up-to-date data. In this study, GHG emission values and their uncertainties of waste treatment systems before and after MSW source segregation in Shanghai were analyzed utilizing Life Cycle Assessment (LCA) methods and Monte Carlo analysis. The results showed that before waste segregation, 21.0∼319 kg CO 2 -eq GHG per tonne was emitted and that -139∼203 kg CO 2 -eq GHG per tonne was emitted after waste source segregation. The source segregation helps to reduce GHG emissions from MSW treatment systems. In the long run, waste to energy incineration was not recommended from GHG perspective and anaerobic digestion has a great potential for GHG emission reductions. [Display omitted] [ABSTRACT FROM AUTHOR]

Biogas recirculation was conducted to improve the performance of two thermophilic anaerobic sequenced batch reactors (ASBRs), in which high concentrations of volatile fatty acids (VFAs) were accumulated. To accelerate degradation of VFAs, facilitating acetate consumption via syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis (SAO-HM) was expected to be effective. Hence, to promote the SAO-HM pathway, hydrogen was removed to create low hydrogen partial pressure (pH2) in reactor RH, yet in reactor RB, hydrogen was not treated. The performance of RB and RH on VFAs degradation and methane production processes was compared at steady stage; the VFAs and soluble microbial products (SMP) in the effluents were monitored. The results showed that lowpH2intensified the SAO reaction, thereby accelerating conversion of acetate to methane, as well as acetate production from glucose and VFAs. Glucose fermentation type was also influenced. VFAs and SMP in the effluents were reduced after the introduction of biogas mixing, which proceeded much faster in RH with lowpH2. Recirculation of low hydrogen biogas with SAO-HM pathway being promoted should be more effective to alleviate high acid level stress and to improve the reactor performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The production and recovery of valuable products in AD are reviewed. • Closed-loop application of the recovered products in AD is proposed. • More long-term and pilot-scale separation studies are needed in field application. • Future opportunities lie in achievement of industrial stable in-situ extraction. Anaerobic digestion, as an eco-friendly waste treatment technology, is facing the problem of low stability and low product value. Harvesting value-added products beyond methane and removing the inhibitory compounds will unleash new vitality of anaerobic digestion, which need to be achieved by selective separation of certain compounds. Various methods are reviewed in this study for separating valuable products (volatile fatty acids, medium-chain carboxylic acids, lactic acid) and inhibitory substance (ammonia) from the liquid fraction of digestate, including their performance, applicability, corresponding limitations and roadmaps for improvement. In-situ extraction that allows simultaneous production and extraction is seen as promising approach which carries good potential to overcome the barriers for continuous production. The prospects and challenges of the future development are further analyzed based on in-situ extraction and economics. [ABSTRACT FROM AUTHOR]

• Composting & anaerobic digestion are efficient ways for attenuating ARGs in biowastes. • Factors, i.e. substrate property, pretreatment, additive and operating condition affect ARGs fate. • ARGs hosts should be identified by combining in situ analysis with culture method. Antibiotic resistance genes (ARGs) in biowaste, such as livestock manure and excess activated sludge, pose potential threat to human and ecological health when applied to agricultural fields. Biological treatment approaches, such as thermophilic composting/vermicomposting and anaerobic digestion, widely adopted to stabilize biowaste have demonstrated significant effects on the fate of ARGs. However, the influence of these biological treatments on ARGs is not known. This review summarizes the occurrence of ARGs in biowaste and the impact of thermophilic composting, vermicomposting, and anaerobic digestion on the fate of ARGs with discussion on factors, including substrate properties, pretreatments, additives, and operational parameters, associated with ARGs during biological treatment of biowaste. Finally, this review explores the research implications and proposes new avenues in the field of biological treatment of organic waste. [ABSTRACT FROM AUTHOR]

• Molecular information for leachate DOM could be the fingerprint of waste landfills and storage pits. • Waste age significantly contributed to such fingerprint profile. • Double-bond equivalent increased and the H/C decreased with waste age. • Relative abundance of 57 molecular formulae significantly correlated with waste age. Waste leachate is a pool of complicated metabolites from waste treatment and disposal as a global environmental problem. The recognition of dissolved organic matter (DOM) in leachate is crucial to improve leachate treatment efficiency and comprehend waste stabilization process. The present study acquired the molecular information for DOM in 22 waste leachate samples using ultra-performance liquid chromatography coupled with hybrid quadrupole Orbitrap mass spectrometry (UPLC Orbitrap MS/MS) based on two dimensions of retention time and mass-to-charge ratio. Unique mass peaks occupied more than 20% of the detected mass peaks in each leachate, implying that the molecular information for DOM could be the fingerprint of waste landfills and storage pits. Waste age and composition predominately accounted for this unique DOM. The double-bond equivalent increased and the H/C decreased with waste age. We further found that 57 precursor ion peaks and artificial matter (confirmed as N-butylbenzenesulfonamide) were significantly correlated with waste age by multiple test and non-target screening. These molecular characteristics of raw leachate were first determined to compensate for the evolution of leachate with waste age. The fingerprints of waste leachate can be further applied in environmental monitoring scenarios, e.g., tracing landfill leakage. [ABSTRACT FROM AUTHOR]

[Display omitted] • A nondestructive method for determining moisture content of solid waste was proposed. • The moisture content prediction model was based on ATR-FTIR spectra and ML algorithm. • An efficient data processing method that used the water-band spectra was proposed. • Hyperparameters of combinations of preprocessing and ML regressors were optimized. • The performance, application prospects and limitations of the models were analyzed. Rapid determination of moisture content plays an important role in guiding the recycling, treatment and disposal of solid waste, as the moisture content of solid waste directly affects the leachate generation, microbial activities, pollutants leaching and energy consumption during thermal treatment. Traditional moisture content measurement methods are time-consuming, cumbersome and destructive to samples. Therefore, a rapid and nondestructive method for determining the moisture content of solid waste has become a key technology. In this work, an attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and multiple machine learning methods was developed to predict the moisture content of multi-source solid waste (textile, paper, leather and wood waste). A combined model was proposed for moisture content regression prediction, and the applicability of 20 combinations of five spectral preprocessing methods and four regression algorithms were discussed to further improve the modeling accuracy. Furthermore, the prediction result based on the water-band spectra was compared with the prediction result based on the full-band spectra. The result showed that the combination model can efficiently predict the moisture content of multi-source solid waste, and the R2 values of the validation and test datasets and the root mean square error for the moisture prediction reached 0.9604, 0.9660, and 3.80, respectively after the hyperparameter optimization. The excellent performance indicated that the proposed combined models can rapidly and accurately measure the moisture content of solid waste, which is significant for the existing waste characterization scheme, and for the further real-time monitoring and management of solid waste treatment and disposal process. [ABSTRACT FROM AUTHOR]

With the implementation of municipal solid waste source segregation, the enormous sorted biogenic waste has become an issue that needs to be seriously considered. Anaerobic digestion, which can produce biogas and extract floating oil for biodiesel production, is the most prevalent treatment in China for waste management and greenhouse gas (GHG) emissions reduction, in accordance with Sustainable Development Goal 13 of the United Nations. Herein, a large-scale biogas plant with a capacity of 1000 tonnes of biogenic waste (400 tonnes of restaurant biogenic waste and 600 tonnes of kitchen biogenic waste) per day was investigated onsite using material flow analysis, and the parts of the biogas plant were thoroughly analyzed, especially the pretreatment system for biogenic waste impurity removal and homogenization. The results indicated that the loss of the total biodegradable organic matter was 41.8% (w/w) of daily feedstock and the loss of biogas potential was 18.8% (v/v) of daily feedstock. Life cycle assessment revealed that the 100-year GHG emissions were −61.2 kgCO 2 -eq per tonne biogenic waste. According to the sensitivity analysis, pretreatment efficiency, including biodegradable organic matter recovery and floating oil extraction, considerably affected carbon reduction potential. However, when the pretreatment efficiency deteriorated, GHG benefits of waste source segregation and the subsequent biogenic waste anaerobic digestion would be reduced. [Display omitted] • A 1000 tonne/day plant handled biogenic waste, emphasizing efficient pretreatment. • Source segregation effectively improved the purity of biogenic waste up to 97.6%. • Pretreatment suffered losses: 41.8% organic and 18.8% biogas potential. • Efficient pretreatment was crucial for maintaining greenhouse gas benefits. [ABSTRACT FROM AUTHOR]

The loess regions distribute widely in Northwestern China, North America and Eastern Europe. For these regions, landfill is a suitable technology for solid waste treatment. However, as a landfill cover material, loess is not very effective in controlling the emission of malodorous gases. The present study modified loess with biologically stabilized leachate, and investigated the capacities and mechanisms of the modified loess to remove odorous NH 3 and H 2 S. The removal rates of NH 3 and H 2 S at different acclimation time, targeted gas concentrations and temperatures were measured. It was found that the NH 3 removal rate of the modified loess was up to 0.08 μmol/(g·hr), which was 1.8 times that of the virgin loess. The H 2 S removal rate of the modified loess was up to 1.74 μmol/(g·hr), which was 1.25 times that of the virgin loess. The half-meter loess layer modified by biologically stabilized leachate achieved nearly 100% removal of H 2 S. The improvement of NH 3 and H 2 S removal ability was mainly due to the enrichment of relevant microorganisms. This work proposed a novel method for in-situ control of malodorous pollutants in landfills in the loess regions, and proved that the in-situ removal of NH 3 and H 2 S using the loess modified with biologically stabilized leachate is feasible and cost-effective. [Display omitted] • An in-situ odor control method for landfills in loess regions was proposed. • Loess was modified with biologically stabilized leachate for landfill cover. • Microbes and functional genes for odor control were enriched after modification. • The highest NH 3 removal rate of loess was increased by 80% after modification. • The highest H 2 S removal rate of loess was increased by 25% after modification. [ABSTRACT FROM AUTHOR]

[Display omitted] • K+, NH 4 +, and Cl− were components with higher migration priority during ED. • Percentage removal of salt ions reached over 90% • ED recovered 35–70% N and P and extracted 70% VFAs from liquid digestate. • Organic molecules with benzene rings and carboxyls were easier to foul the membrane. • Agriculture application and VFAs products showed economic benefits about 20 USD/t-digestate. With the wider application of anaerobic digestion in food waste treatment, the digestate management becomes the bottleneck either from economic or carbon mitigating point. The high salt content in food waste digestate hinders the mass agriculture application. In this study, electrodialysis was performed to assess the performance of desalting from mature and fresh liquid digestate as well as the migration patterns of nutrients and value-added products. K+, NH 4 +, and Cl− were found to be the components with higher migration priority. Current efficiency (CE) for desalination scenario was about 35–50% while NH 4 + in mature digestate (MD) contributed about 50–55% of the cationic CE and volatile fatty acids (VFAs) in fresh digestate (FD) contributed about 20–25% of the anionic CE. Organic carbon in MD was well retained, whereas 49%-63% organic carbon in FD experienced migration, which is more obvious at neutral pH. Electrodialysis removed over 90% salts and recovered 35–70% N and P from both mature and fresh liquid digestate, and extracted 70% VFAs from FD. This is expected to save the cost in wastewater treatment of 19.46 USD/t-digestate or obtain a benefit of 17.36USD/t-digestate from VFAs product. But the membrane fouling brought great uncertainty to the operating costs. Compared with cation exchange membrane, more severe membrane fouling was found in anion exchange membrane, whose performance decreased to half of the original by the end of the experiment. Organic molecules with benzene rings and carboxyls were mainly responsible for the membrane fouling. [ABSTRACT FROM AUTHOR]

Pyrolysis of plastics is a promising technique towards high-value utilization and solvent-free treatment of plastic waste. However, low product selectivity and broad product distribution may restrict the application of plastic pyrolysis. In this study, polyolefins and polystyrene (PS) were converted into methane and carbon spheres through pyrolysis under autogenic atmosphere (AAP). To elucidate the product evolution and reaction mechanism of AAP, product distributions, compositions and properties at 450–700 °C were investigated. At 450 °C, polyolefins were converted into 89.3–96.91 wt% pyrolysis oil; PS was converted into 88.4 wt% of pyrolysis oil, 2.3 wt% of gas and 9.3 wt% of char. As the increase of temperature, the yields of methane and pyrolysis char increased significantly. At 700 °C, the yields of pyrolysis chars were as high as ~45 wt% and 74.1 wt% for polyolefins and PS, respectively, and the rest products was mainly pyrolysis gas with less than 1 wt% of pyrolysis oil. Pyrolysis chars were well carbonized spheres with diameters of 2 − 8 µm. Pyrolysis gas contained 93.83–95.74 vol% of methane, and possessed higher heating values of 35.8–36.2 MJ m−3. The pyrolysis products with high purity and narrow distribution can be attributed to the enhancement of AAP on the secondary reactions of primary decomposition products, such as cracking, hydrogenation, aromatization and condensation. • Polyolefins and PS were converted into methane-rich syngas and carbon spheres. • Enhancing temperature increased methane and carbon yields and reduced oil yields. • AAP enhanced the reactions of hydrogenation, aromatization and condensation. • Polyolefins and PS exhibited different laws of product characters. [ABSTRACT FROM AUTHOR]

• Recycled biochar-biofilm consortia demonstrated feasible long-term application in AD. • Biochar < 5 μm more efficiently initiated methanogenesis than biochar > 1 mm. • Biochar < 5 μm enriched 20 times more microorganisms than larger biochar. • Methanosarcina dominated in biochar > 1 mm, while SAOB dominated in biochar < 5 μm. Several single dose studies found that biochar was an effective additive promoting methanogenesis in anaerobic digestion. However, little attention was paid to the continuity of the biofilm formed on biochar and the subsequent evolution of microorganisms. In this study, the continuous performance and changes were quantified when biochar-biofilm consortia were applied as the recyclable inoculant to four cycles of acetate methanogenesis with increasing acetate loading. Biochar-biofilm consortia as the inoculant were found to consistently realize stable methane production, despite the removal of planktonic microorganisms in the reactor, and no extra inoculum and biochar were added. Consortia with biochar particles smaller than 5 μm promoted initiation of methanogenesis more rapidly than those with biochar particles larger than 1 mm, especially when the activity of microorganism was low. Moreover, the microorganisms were enriched throughout the continuous cycles. Biochar < 5 μm was found to accumulate 6.6–7.1 E + 11 16S copies per gram in the 3rd and 4th cycles, which was about 27–51 times that of biochar > 1 mm and also comparable to a fresh sludge inoculum. In addition, specific functional methanogens proliferated during continuous application. Methanosarcina was dominant in biochar > 1 mm, while the syntrophic acetate oxidizing bacteria Thermovirga and Mesotoga accounted for the majority of microorganisms in biochar < 5 μm. Therefore, with the competitive total cell count dominated by functional microorganisms, biochar-biofilm consortia demonstrated feasible recycling and reuse for bioaugmentation purposes or in the economical long-term application of anaerobic digestion for waste or wastewater treatment. [ABSTRACT FROM AUTHOR]